Pressure gauge



Jan. 2 1, 1928.

R. D. ST. JOHN PRES SURE GAUGE Filed Sept. 14. 1926 Roy 0. Jo /7 Patented J an. .24, 1928.

when

ROY D.. ST. JOITIN, OFS POKANE, WASHINGTON.

PRESSURE GAUGE.

Application-filed September 14, 1926'. Serial No. 135,341.

Mypresent invention relates to -improvements inpressure gauges, which. while ape pile-able :lor usc;in nun'ierous waysand. tor

various purposes is especially adaptedyfoir measuring and indicatingthe compression in.- the cylinders of internal combustion engines.

In the utilization of'thedevice of my invention the sparkplug isuremoved from the.

engine and the gauge is applied to the spark plug opening in position to receive separate impulses from the engineand indicate and measure the'compression. Means are also provided in connection with the pressure gauge for retaining the accuniiulated pressure in the gauge from succeeding or succesaix impulses of the engine to measure and indicate the maximum compression generated in the engine cylinder.

The invention consists in certain novel combinations and arrangements of parts for accomplishing the above indicated results as will hereinafter be more fully pointed out and claimed.

In the accompanying drawings I have indicated and illustrated one complete example of the physical embodiment of my invention wherein the parts are combined and arranged according to the best mode I have thus far devised for the practical application of the principles of my invention.

Figure l is a view in elevation showing the gauge of my invention applied for use.

Figure 2 an enlarged vertical sectional view showing a plurality of selective attaclr ing nipples tor the device, and the check ralve mechanism tor retaining the pressure in the gauge.

Figure 23 is a transverse sectional view at line S 4 of ligure 1.

,l igure 4 is a transverse sectional view at line l;--tof Figure 1.

Figure 1 of the drawings shows the gencral assei'nbly and arrangement of parts, wherein a pressure gauge of the well known llourdon type is indicated as a whole by the numeral 1. A portion of the spiral pressure tube 2 of the gauge is indicated in Figure 2, and the usual dial 3 and exterior point-er or indicator 4 are shown in Figure 1 to measure and indicate the pressure in the pressure tube.

The gauge is equipped with a specially constructed inlet pipe or tubular stem 5 to which the spiral pressure tube 2 is connected within the gauge casing, and at the lower end of the tubular stem are provided the usual exterior. threads by. means of which the ge may. be attached. to a cylinder as 6 in Figural. By displacingthe spark plug and, threading thelower end of the tubular stem into the spark plug opening or the cylinden the gauge may bevused to measure and indicate thesingle impulses or comprea sionfronrthe cylinder.- As the pressure is applied to the gauge the indicator swings in usual manner to-anieasure and indicate the degreeo-i compression on the, dial 3, and then the *indicator returns to normal or Zero position.

For retaining the accumulated pressure from successive impulses of compression by the piston in the cylinder, 1 utilize a checkvalve n'iechanism between the cylinder and gauge, which mechanism is preferably lo cated in the tubular stem. For this purpose I use a ball valve 7 in the tubular stem above an interior bushing 8 having a valve seat 9 at its upper end, and the coiled spring 10 located above the ball valve normally holds the latter in its seat 9. As the successive pressure impulses from the strokes ol the piston inthe cylinder are forced past the spring pressed check valve into the gauge the pressure in the gauge is increased there-- in, and the degree of compression is indicated on the dial by the indicator or hand l.

When desired, the accumulated or maximum pressure, or the pressure from single impulses of the engine, may be released :lrom the gauge by manually controlled means in connection with the valve stem ll of the check valve, which stem extends downward ly from the ball. valve through the bushing 8 in the tubular stem 5.

At its lower end the valve stem is providedavith a pair of spaced heads 12 and 13, and a crank arm 14 on the end of a rotary pin 15 is interposed between these heads and connected to the valve stem in such manner that when the pin is turned the check valve may be lifted from its seat to release the pressure in the gauge.

The pin projects at right angles from the valve stem and is journaled to turn in a screw plug or nut 16 used as a bearing for the pin. A knurled head 17 is fixed on the exterior end of the pin for convenience in turning it.

To adapt the device for use with cylinder heads having different sizes of threaded spark plug openings, or screw threads 01 various pitch, I employ a plurality of into ice riorly thread-ed and exterior-1y threaded nipples as 18, 19 and 20, shown in Figure 2 and threaded together for attachment to a cylinder head. As here shown the releasing pin for opening the check valve is supported or journaled in the plug 16 which is threaded in the nipple l8.

The nipple 18 as shown has an exterior threaded end of greater diameter than the nipples l9 and 20, and these latter nipples before it is applied to the cylinder, and the ratchet head 21 which engages one of the nipples or nuts, is turned by means of the handle 22 extending laterally therefrom, a pair of reversing pawls or 'atchets 23 and 2a being used with the head, and a shifting lever 25' is utilized for shifting the pawls in well known manner.

Having thus fully described my invention, what 1 claim as new and desire to secure by Letters Patent is The combination with a pressure gauge having a tubular attaching stem and a bush-* ing therein having a valve seat, 01' a spring pressed check valve of the ball type in said seat, a valve stem, an angnlarly disposed release pin, and connections between said pin and stem for manually ren'ioving said valve from its seat.

In testimony whereof I aliix my signature.

ROY 1). ST. JOHN. 

